This invention is based on the discovery of flame retarded reinforced molding compositions based on poly(1,4-cyclohexylene dimethyl terephthalate) or high melting crystalline copolymers thereof with improved mechanical properties. Generally, polyesters are flame retarded by using brominated organic compounds in combination with antimony oxide. Surprisingly, by replacing the antimony oxide with powdered antimony metal in these formulations, the mechanical properties are greatly enhanced while maintaining the excellent flammability properties. Flame retarded glass fiber reinforced polyester containing the powdered antimony metal has excellent strength, heat resistance, and flammability properties. These materials would find application in the electronics industry where flame retarded materials are necessary.
The use of antimony oxide in combination with brominated organic compounds is well known in the art of flame retarded polymers. Sodium antimonate used in combination with brominated organic compounds and used as a replacement for antimony oxide to flame retard poly(ethylene terephthalate) is disclosed in U.S. Pat. No. 4,338,243. We are unaware of any prior art on the use of powdered antimony metal in combination with brominated organic compounds to flame retard polymers.